This invention pertains to devices for testing pool water conditions, and more particularly, to such an instrument which automatically measures a predetermined volume of reagent and transfers it to the water sample.
In order to maintain a contained pool of water, as would be found in a swimming pool, hot tub or spa pool, in a desired condition, it is necessary to measure certain conditions of the water. During measurement of a particular condition, a predetermined volume of a reagent or indicator solution is added to a predetermined volume of sampled water. Most commonly, the pH and chlorine levels are determined. The test reagents now generally used are orthotolidine for testing chlorine and phenol red for pH level. Orthotolidine, when added to water containing chlorine, turns the water various colors of yellow depending on the concentration of chlorine in the water. Similarly, the addition of phenol red to the water sample turns the sample various shades of red depending on the pH of the water. The importance of proper pH and chlorine balance are well-known in the trade.
Typical simplified portable test kits provide a pair of clear vials mounted in a holder next to color charts which show the various concentration levels of a specified water condition. The two vials are submerged in a pool of water to fill them to a desired level. Then, a specified number of drops of appropriate reagents are dispensed into the water samples. The resulting water color is compared with the associated charts to determine the condition of the pool water. Changes may then be made in the water condition to bring it to a desired level. Although these kits have very simple structure and are inexpensive to make, they do not provide consistent measurement results because the drop sizes vary.
More involved apparatus have also been developed in an attempt to improve the reliability of the testing process. These devices typically are rather complex and have several different moving parts. One such instrument is shown in U.S. Pat. No. 3,692,490 to Hall. The instrument is submerged in a pool and a pair of concentric-shafted T-handles are brought together to draw sample pool water into a reservoir created by the shifting of the handles. A sample of reagent is simultaneously forced through a one-way valve from a reagent reservoir into the water reservoir. Venting of the reagent chambers is provided through the shaft of one of the handles, the top of which must be maintained above water level. Further, an entry port which allows entry of the sample water is made small, so that water will not drain out of it when the instrument is held out of the water for observing the resulting color of the water. Further, there is involved valving provided to assure that reagent rather than water is replaced in a plunger cylinder forming part of the reagent supply cylinder during a water-ejecting phase after the test has been performed. The complex structure of these devices makes them more expensive to produce and are subject to operational malfunction.
Another, more simple, device is disclosed in U.S. Pat. No. 3,910,764 issued to Tower which shows a hand-held device containing a spring biased slide to cover a water sample reservoir and a spring biased one-way valve injection plunger for drawing water from a reagent reservoir and forcing it into the water chamber. A special dimple is provided in the slide which covers the water chamber to accommodate the increased volume provided by the injection of the reagent. In this device there is no vent to allow the reagent supply chamber to accommodate the withdrawal of reagent from it during testing. Further, the accuracy of reagent supply injected into a water sample will vary depending upon the amount of reagent which remains in a conduit housing a spring and valve through which the dispensed reagent must pass. Although fairly simple to use, the various springs and valving make it relatively expensive to produce.
Fixed position liquid testing instruments have been developed which, besides not being handheld or portable, rely on a pressurized flow of water through them for operation. One such instrument is disclosed in U.S. Pat. No. 3,169,834 issued to Otto et al. which is used with a pressurized supply of a liquid to be tested. It provides an involved channeling scheme which is used to fill a mixing chamber during a testing procedure, to bypass that mixing chamber when it has been filled, and to flush it after a test has been completed. It includes a plunger which transfers a metered amount of reagent into an upstream channel where it is washed down into a mixing chamber having a drain. A plunger which transfers the reagent also closes the drain. If the movement of the plunger to the drain-closing position is not done quickly enough, some reagent may easily be washed out of the mixing chamber before a measurement can be made. This instrument is not usable in a contained pool test environment where a pressure supply system is not readily available. Further, it is not portable for transportation to a pool to obtain a water sample and then removal therefrom so that it does not interfere with the pool environment between testing operations.
The present invention provides a simplified portable hand-held, pool-water test instrument for transferring a predetermined volume of a reagent into a predetermined volume of water obtained from a contained pool. Means are included for providing a supply of reagent and for holding a predetermined volume of water which is spaced from the reagent supply. Means are also included for introducing sample water into the instrument and for transferring reagent from the reagent supply into the sample water. The reagent transferring is preferably provided by means defining a measuring chamber which is shiftable between a loading position where it is fillable with a predetermined volume of reagent and a mixing position where it is mixable with the sample water.
The preferred embodiment of the invention includes a reagent supply chamber which is sealable from the atmosphere and a separate mixing chamber capable of holding sample water. A slide disposed below the reagent chamber has the measuring chamber which is positionable in communication with the reagent supply chamber for filling with reagent. The slide is then shifted to the mixing position where the measuring chamber is open to the mixing chamber. Sample water is introduced into the mixing chamber through external ports which are sealable from the atmosphere by doors joined with the slide. The doors are shifted into positions covering the ports as the slide is shifted to the mixing position.
This invention provides a self-venting instrument which may be used repeatedly so long as sufficient reagent supply exists. Further, it provides for simplified operation in that only a single slide moves during operation of the instrument. Further, no valves are used since reagent is transferred by a simple slide movement. These and additional features and advantages of the present invention will be more clearly understood from a consideration of the drawings and the following detailed description of the preferred embodiment.